This invention relates to a tip for a pipette used for transferring a specified amount of liquid from one vessel into another vessel and a pipette with the tip.
A pipette is generally used, for example, when a sample of liquid for an analysis is transferred from a vessel for sample picking into a vessel for an analysis. As a pipette of such kind, there is known one which has a small-diameter nozzle formed at a tip end of a body vessel and a suction chamber formed in a middle part of the body vessel.
The nozzle of the pipette is put in a liquid in the vessel for sample picking with the suction chamber compressed, and the suction chamber is then reduced in pressure so that the pipette sucks a liquid sample. Thereafter, the nozzle is inserted into the vessel for an analysis, and the suction chamber is then compressed again so that the pipette discharges the sucked liquid sample into the vessel for an analysis. In this manner, the liquid sample is transferred from the vessel for sample picking to the vessel for an analysis.
The above-mentioned convention pipette is a fixed-capacity type one in which the amount of a single suction of liquid sample is fixed. Therefore, its range of use is limited, which invites poor versatility. For example, when urinalysis is carried out in a physical checkup or the like, picked urine is first centrifuged, the supernatant fluid is then removed and 200 xcexcl of liquid sample is prepared. Thereafter, 200 xcexcl of liquid sample and the residue are mixed and from the mixture thus obtained, 15 xcexcl of liquid sample for a urine precipitation test is picked up.
Thus, since the amount of suction of the conventional pipette is fixed, 200 xcexcl sampling and 15 xcexcl sampling cannot readily be set, resulting in expending much time and effort in carrying out urinalysis.
To cope with this, there is proposed a variable-capacity type pipette which is variable in sampling amount, as disclosed in Japanese Patent Application Laid-Open Gazette No. 8-332397. In this pipette, however, since a tip is simply fitted to a nozzle, this makes it difficult to determine whether or not the attachment of the tip to the nozzle has been fully completed.
In particular, the tip as mentioned above requires detachment and replacement with a new one for each sampling. In addition, there is a strong demand for prompt analyses of a large number of samples. Therefore, the tip should be attached to the nozzle with ease and reliability and simultaneously should be detached therefrom with ease. Additionally, since it is necessary that the pipette ensures providing a constant sampling amount at any time, a reliable seal must be formed between the tip and the nozzle. As a result, two opposing requirements, i.e., ensured sealing property and ease of detachment, must be satisfied.
The present invention has been made in view of the foregoing problems and therefore has its object of making a tip readily detachable from a pipette and providing ensured sealing property between the tip and a nozzle of the pipette.
To attain the above object, a first solution of the present invention is directed to a tip freely attachable to and detachable from a nozzle of a pipette. And, the tip includes: a tapered tip body having an elongated cylindrical form; a nozzle-fitting part formed in a root portion of the tip body; an annular part formed along an inner periphery of the nozzle-fitting part to extend inwardly therefrom for close contact with an outer periphery of the nozzle; and a thick portion formed around an outer periphery of an end portion of the nozzle-fitting part to extend outwardly therefrom for abutment against a tip releasing member for detaching the tip body from the nozzle of the pipette.
In a second solution of the present invention, the nozzle of the pipette in the first solution includes a root portion, a tip attachment part formed smaller in diameter than the root portion and continuously therefrom through a shoulder, and an annular part formed around an outer periphery of the tip attachment part to extend outwardly therefrom. Further, the annular part of the tip body is formed to be closely contactable with the annular part of the nozzle and to reach a position where a feeling of fitting between the tip body and the nozzle is provided through the abutment of an end surface of the nozzle-fitting part of the tip body against the shoulder of the nozzle at the completion of fitting of the tip body onto the nozzle. In addition, the thick portion of the nozzle-fitting part of the tip body is formed larger in diameter than the root portion of the nozzle to be located outside the root portion of the nozzle for abutment against the tip releasing member freely movable in an axial direction of the nozzle.
In a third solution of the present invention, both the annular parts of the nozzle and the tip body in the second solution are each formed into a projection of half-round cross section, and the annular part of the tip body is formed to complete the fitting of the tip body onto the nozzle by snapping over the annular part of the nozzle.
A fourth solution of the present invention is directed to a pipette. The pipette includes: a cylindrical casing; a cylinder provided in the casing; a suction chamber formed in the cylinder; a nozzle which is continuously formed at an outward end of the cylinder to extend to the outside of the casing and has a suction passage in communication with the suction chamber; at least one piston which is provided in the casing and is reciprocatably inserted into the suction chamber to suck and discharge liquid; and a tip freely attachable to and detachable from the nozzle.
The nozzle includes a root portion, a tip attachment part formed smaller in diameter than the root portion and continuously from the root portion through a shoulder, an annular part formed around an outer periphery of the tip attachment part to extend outwardly therefrom, and a tip releasing member provided outside of the root portion and freely movable in an axial direction of the nozzle.
The tip includes a tapered tip body having an elongated cylindrical form, a nozzle-fitting part formed in a root portion of the tip body, an annular part which is formed along an inner periphery of the nozzle-fitting part to extend inwardly therefrom and closely contacts with the annular part of the nozzle, and a thick portion formed around an outer periphery of an end portion of the nozzle-fitting part to extend outwardly therefrom and having a larger diameter than that of the root portion of the nozzle to be abuttable against the tip releasing member.
A fifth solution of the present invention is directed to a pipette. The pipette includes a cylindrical casing; a cylinder formed at an inner tip end of the casing; a first suction chamber which is formed in the cylinder and is open on an inward end surface of the cylinder; a nozzle which is formed at an outward end of the cylinder to extend to the outside of the casing and has a suction passage in communication with the first suction chamber; and a first piston reciprocatably inserted into the first suction chamber.
Further, the pipette includes: a second suction chamber which is formed in the first piston and is open on both end surfaces of the first piston; a second piston reciprocatably inserted into the second suction chamber, the second piston including a small-diameter part insertable into the second suction chamber and a large-diameter part engageable with the first piston to push the first piston; a first resilient member which pushes the first piston in a direction of protruding from the cylinder; and a second resilient member which pushes the second piston in a direction of protruding from the first piston, the second resilient member having less resiliency than the first resilient member.
In addition, the pipette includes: an operating lever which is provided in the casing, comes into contact at an inward end thereof with a top surface of the second piston, and operates the first and second pistons to switch between a small suction position where the second piston is extremely retracted in the first piston and a large suction position where the first and second pistons are extremely retracted in the cylinder and the first piston, respectively; and a tip freely attachable to and detachable from the nozzle.
The nozzle includes a root portion, a tip attachment part formed smaller in diameter than the root portion and continuously from the root portion through a shoulder, an annular part formed around an outer periphery of the tip attachment part to extend outwardly therefrom, and a tip releasing member provided outside of the root portion and freely movable in an axial direction of the nozzle.
The tip includes a tapered tip body having an elongated cylindrical form, a nozzle-fitting part formed in a root portion of the tip body, an annular part which is formed along an inner periphery of the nozzle-fitting part to extend inwardly therefrom and closely contacts with the annular part of the nozzle, and a thick portion formed around an outer periphery of an end portion of the nozzle-fitting part to extend outwardly therefrom and having a larger diameter than that of the root portion of the nozzle to be abuttable against the tip releasing member.
A sixth solution of the present invention is directed to a pipette. The pipette includes: a cylindrical casing; a cylinder formed at an inner tip end of the cylindrical casing; a first suction chamber which is formed in the cylinder and is open on an inward end surface of the cylinder; a nozzle which is formed at an outward end of the cylinder to extend to the outside of the casing and has a suction passage in communication with the first suction chamber; a first piston which is reciprocatably inserted into the first suction chamber; a second suction chamber which is formed in the first piston and is open on both end surfaces of the first piston; and a second piston which is reciprocatably inserted into the second suction chamber.
The pipette further includes: a first resilient member which pushes the first piston in a direction of protruding from the cylinder, the first resilient member surrounding the second suction chamber; and a second resilient member which pushes the second piston in a direction of protruding from the first piston, the second resilient member having less resiliency than the first resilient member.
Further, the pipette includes: an operating lever which is provided in the casing, comes into contact at an inward end surface thereof with a top surface of the second piston, and operates the first and second pistons to switch between a small suction position where the second piston is extremely retracted in the first piston and a large suction position where the first and second pistons are extremely retracted in the cylinder and the first piston, respectively; and a tip freely attachable to and detachable from the nozzle.
The nozzle includes a root portion, a tip attachment part formed smaller in diameter than the root portion and continuously from the root portion through a shoulder, an annular part formed around an outer periphery of the tip attachment part to extend outwardly therefrom, and a tip releasing member provided outside of the root portion and freely removable in an axial direction of the nozzle.
The tip includes a tapered tip body having an elongated cylindrical form, a nozzle-fitting part formed in a root portion of the tip body, an annular part which is formed along an inner periphery of the nozzle-fitting part to extend inwardly therefrom and closely contacts with the annular part of the nozzle, and a thick portion formed around an outer periphery of an end portion of the nozzle-fitting part to extend outwardly therefrom and having a larger diameter than that of the root portion of the nozzle to be abuttable against the tip releasing member.
In a seventh solution of the present invention, both the annular parts of the tip and the nozzle in any one of the fourth through sixth solutions are provided to reach a position where a feeling of fitting between the tip and the nozzle is provided between a root end surface of the nozzle-fitting part of the tip and the shoulder of the nozzle at the completion of fitting of the tip onto the nozzle.
In an eighth solution of the present invention, both the annular parts of the nozzle and the tip in any one of the fourth through sixth solutions are each formed into a projection of half-round cross section, and the annular part of the tip is formed to complete the fitting of the tip onto the nozzle by snapping over the annular part of the nozzle.
A ninth solution of the present invention is constructed such that in any one of the fourth through sixth solutions, a resilient member for pushing the tip releasing member in a direction away from a distal end of the nozzle is interposed between a tip end of the casing and the tip releasing member, and detaching means is provided for moving the tip releasing member to release the tip from the nozzle.
In the above-mentioned solutions of the invention, first, the tip is connected to the cylinder by fitting the tip onto the nozzle. In this case, when the nozzle is inserted into the tip, the annular part of the tip slides over the annular part of the nozzle. At the completion of insertion of the nozzle into the tip, a feeling of fitting such as an abutment sound is provided between the end surface of the tip and the shoulder of the nozzle. The analyzer recognizes the completion of insertion based on this feeling of fitting.
When the fitting between the tip and the nozzle is completed, both the annular parts of the tip and the nozzle are closely contacted with each other so that a seal is formed between the tip and the nozzle. Then, the piston is reciprocated to suck liquid.
More specifically, in the fifth and sixth solutions, the first piston extends from the cylinder and the second piston extends from the first piston. In a state that the first and second pistons are in their extreme extended positions, the operating lever is pushed. At the time, the casing is gripped with one hand of the analyzer and a push part of the operating lever is pushed with a thumb of the hand.
Through the push of the operating lever, the second piston is initially pushed down. At this time, since the resiliency of the first resilient member is smaller than that of the second resilient member, the second piston is first inserted into the second suction chamber. As a result, the capacity of the second suction chamber is reduced. When the operating lever is further pushed down, the second piston is inserted to a deepest position into the second suction chamber so that the second piston is set in the small suction position for sampling a small amount of liquid.
When the operating lever is still further pushed down, the second piston pushes the first piston downward so that the first piston moves in the first suction chamber. As a result, the capacity of the first suction chamber is reduced. Then, when the operating lever is pushed down to the deepest position, the first piston is inserted to a deepest position into the first suction chamber so that the first piston is set in the large suction position for sampling a large amount of liquid.
In this manner, at the push of the operating lever, sampling a small amount of liquid and sampling a large amount of liquid are selectively executed.
For detachment of the tip from the nozzle, the tip releasing member is moved downward by the detaching means in the ninth solution. When being moved, the tip releasing member abuts against the thick portion of the tip thereby releasing the tip.
According to the present invention, since the annular part provided along the inner periphery of the tip forms a seal between the tip and the nozzle, the attachment of the tip can be made with reliability. As a result, a large number of samples can be analyzed promptly and reliably.
In particular, since the annular parts, provided in the tip and the nozzle, respectively, form a seal therebetween and a feeling of fitting therebetween is provided at the position where the insertion of the nozzle into the tip is completed, the attachment of the tip can be correctly recognized.
Further, though the tip is required to be detached for each sampling and replaced with a new one, the pipette of the present invention enables prompt analyses of a large number of samples in such a case.
Furthermore, since the annular part of the tip comes into close contact with the annular part of the nozzle by snapping over the annular part of the nozzle, a seal can reliably be provided between the tip and the nozzle. Accordingly, sucking liquid can be made correctly, which provides an improved analyzing accuracy.
Moreover, the release of the tip is implemented by simply snapping out the annular part of the tip over the annular part of the nozzle, and therefore a contact area between the tip and the nozzle is small. Accordingly, the release of the tip can be made readily. As a result, the tip can be released with one hand, which provides improved workability.
If the detaching means is provided, the tip can be detached by simply operating the detaching means. As a result, samples are prevented from making contact with a hand, which enables the analysis or the like to be executed in a prompt and considerably sanitary manner.
Further, since the first and second pistons are both inserted to a deepest position into the cylinder and are reciprocated, selection can be made between a large amount sampling and a small amount sampling. As a result, the pipette of the present invention provides an extended range of applications as compared with the conventional pipette whose sampling amount is limited to a fixed amount. In particular, when a large number of samples are analyzed, a necessary amount of liquid can readily be sampled, which achieves prompt analyzing.
Furthermore, since the pipette of the present invention can simplify the structure and reduce the number of parts as compared with the conventional pipette of the capacity-variable type whose sampling amount is arbitrarily set, this reduces the manufacturing cost.
Moreover, selection between the large amount sampling and the small amount sampling can be made with one hand, i.e., at the push of the push part with a thumb. As a result, operation can be simplified thereby speeding up the execution of various kinds of analyses.